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bigint(3p)       Perl Programmers Reference Guide      bigint(3p)


NAME
       bigint - Transparent BigInteger support for Perl

SYNOPSIS
         use bignt;

         $x = 2 + 4.5,"\n";                    # BigInt 6
         print 2 ** 512,"\n";                  # really is what you think it is
         print inf + 42,"\n";                  # inf
         print NaN * 7,"\n";                   # NaN

DESCRIPTION
       All operators (including basic math operations) are over-
       loaded. Integer constants are created as proper BigInts.

       Floating point constants are truncated to integer. All
       results are also truncated.

       OPTIONS

       bigint recognizes some options that can be passed while
       loading it via use.  The options can (currently) be either
       a single letter form, or the long form.  The following
       options exist:

       a or accuracy
         This sets the accuracy for all math operations. The
         argument must be greater than or equal to zero. See
         Math::BigInt's bround() function for details.

                 perl -Mbigint=a,2 -le 'print 12345+1'

       p or precision
         This sets the precision for all math operations. The
         argument can be any integer. Negative values mean a
         fixed number of digits after the dot, and are
         <B>ignored</B> since all operations happen in integer
         space.  A positive value rounds to this digit left from
         the dot. 0 or 1 mean round to integer and are ignore
         like negative values.

         See Math::BigInt's bfround() function for details.

                 perl -Mbignum=p,5 -le 'print 123456789+123'

       t or trace
         This enables a trace mode and is primarily for debugging
         bigint or Math::BigInt.

       l or lib
         Load a different math lib, see "MATH LIBRARY".

                 perl -Mbigint=l,GMP -e 'print 2 ** 512'




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bigint(3p)       Perl Programmers Reference Guide      bigint(3p)


         Currently there is no way to specify more than one
         library on the command line. This will be hopefully
         fixed soon ;)

       v or version
         This prints out the name and version of all modules used
         and then exits.

                 perl -Mbigint=v -e ''

       MATH LIBRARY

       Math with the numbers is done (by default) by a module
       called Math::BigInt::Calc. This is equivalent to saying:

               use bigint lib => 'Calc';

       You can change this by using:

               use bigint lib => 'BitVect';

       The following would first try to find Math::BigInt::Foo,
       then Math::BigInt::Bar, and when this also fails, revert
       to Math::BigInt::Calc:

               use bigint lib => 'Foo,Math::BigInt::Bar';

       Please see respective module documentation for further
       details.

       INTERNAL FORMAT

       The numbers are stored as objects, and their internals
       might change at anytime, especially between math opera-
       tions. The objects also might belong to different classes,
       like Math::BigInt, or Math::BigInt::Lite. Mixing them
       together, even with normal scalars is not extraordinary,
       but normal and expected.

       You should not depend on the internal format, all accesses
       must go through accessor methods. E.g. looking at
       $x->{sign} is not a good idea since there is no guaranty
       that the object in question has such a hash key, nor is a
       hash underneath at all.

       SIGN

       The sign is either '+', '-', 'NaN', '+inf' or '-inf' and
       stored seperately.  You can access it with the sign()
       method.

       A sign of 'NaN' is used to represent the result when input
       arguments are not numbers or as a result of 0/0. '+inf'
       and '-inf' represent plus respectively minus infinity. You



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bigint(3p)       Perl Programmers Reference Guide      bigint(3p)


       will get '+inf' when dividing a positive number by 0, and
       '-inf' when dividing any negative number by 0.

       METHODS

       Since all numbers are now objects, you can use all func-
       tions that are part of the BigInt API. You can only use
       the bxxx() notation, and not the fxxx() notation, though.

       CAVEAT

       But a warning is in order. When using the following to
       make a copy of a number, only a shallow copy will be made.

               $x = 9; $y = $x;
               $x = $y = 7;

       Using the copy or the original with overloaded math is
       okay, e.g. the following work:

               $x = 9; $y = $x;
               print $x + 1, " ", $y,"\n";     # prints 10 9

       but calling any method that modifies the number directly
       will result in both the original and the copy beeing
       destroyed:

               $x = 9; $y = $x;
               print $x->badd(1), " ", $y,"\n";        # prints 10 10

               $x = 9; $y = $x;
               print $x->binc(1), " ", $y,"\n";        # prints 10 10

               $x = 9; $y = $x;
               print $x->bmul(2), " ", $y,"\n";        # prints 18 18

       Using methods that do not modify, but testthe contents
       works:

               $x = 9; $y = $x;
               $z = 9 if $x->is_zero();                # works fine

       See the documentation about the copy constructor and "="
       in overload, as well as the documentation in BigInt for
       further details.

MODULES USED
       "bigint" is just a thin wrapper around various modules of
       the Math::BigInt family. Think of it as the head of the
       family, who runs the shop, and orders the others to do the
       work.

       The following modules are currently used by bigint:




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bigint(3p)       Perl Programmers Reference Guide      bigint(3p)


               Math::BigInt::Lite      (for speed, and only if it is loadable)
               Math::BigInt

EXAMPLES
       Some cool command line examples to impress the Python
       crowd ;) You might want to compare them to the results
       under -Mbignum or -Mbigrat:

               perl -Mbigint -le 'print sqrt(33)'
               perl -Mbigint -le 'print 2*255'
               perl -Mbigint -le 'print 4.5+2*255'
               perl -Mbigint -le 'print 3/7 + 5/7 + 8/3'
               perl -Mbigint -le 'print 123->is_odd()'
               perl -Mbigint -le 'print log(2)'
               perl -Mbigint -le 'print 2 ** 0.5'
               perl -Mbigint=a,65 -le 'print 2 ** 0.2'

LICENSE
       This program is free software; you may redistribute it
       and/or modify it under the same terms as Perl itself.

SEE ALSO
       Especially bigrat as in "perl -Mbigrat -le 'print
       1/3+1/4'" and bignum as in "perl -Mbignum -le 'print
       sqrt(2)'".

       Math::BigInt, Math::BigRat and Math::Big as well as
       Math::BigInt::BitVect, Math::BigInt::Pari and  Math::Big-
       Int::GMP.

AUTHORS
       (C) by Tels <http://bloodgate.com/>; in early 2002, 2003.

























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